Water soluble triglyceride compositions and method for their preparation

ABSTRACT

Water soluble mixed ester lubricants derived from triglycerides are obtained by transesterifying a triglyceride with a low molecular weight polyoxyethylene glycol in the presence of shortchain mono- or dicarboxylic acids. The mixed ester compositions of this invention are readily water soluble and are excellent lubricants for metalworking operations. Water solubility is achieved with the present mixed ester products even though they have higher triglyceride contents than previously known ester lubricants.

United States Patent [191 Sturwold et al.

[ WATER SOLUBLE TRIGLYCERIDE COMPOSITIONS AND METHOD FOR THEIRPREPARATION [75] Inventors: Robert J. Sturwold; Fred 0. Barrett,

both of Cincinnati, Ohio [73] Assignee: Emery Industries, Inc.,Cincinnati,

Ohio

[22] Filed: Jan. 31, I974 [2|] Appl. No.: 438,283

[58] Field of 260/404.8, 410.6, 410.7; 252/493, 56 S [56] ReferencesCited UNITED STATES PATENTS 2,40l,966 6/l946 Salathiel 260/4l0.6 X

[451 Dec. 23, 1975 2,925,549 2/ I960 Kirkpatrick 260140448 3,042,5307/l962 Kidger 260/4043 X 3,720,695 3/1973 Meisters 260/4l0.6 X

[57] ABS I'RACT Water soluble mixed ester lubricants derived fromtriglycerides are obtained by transesterifying a triglyceride with a lowmolecular weight polyoxyethylene glycol in the presence of short-chainmonoor dicarboxylic acids. The mixed ester compositions of thisinvention are readily water soluble and are excellent lubricants formetalworking operations. Water solubility is achieved with the presentmixed ester products even though they have higher triglyceride contentsthan previously known ester lubricants. l

6 Claims, No Drawings WATER SOLUBLE TRIGLYCERIDE COMPOSITIONS AND METHODFOR THEIR PREPARATION BACKGROUND OF THE INVENTION The reaction oftriglycerides and polyoxyethylene glycols to obtain mixed esters isknown. For example, British Patent No. 847,517 shows the reaction of twomols triglyceride with one mol polyoxyethylene glycol at an elevatedtemperature in the presence of a catalyst to obtain partialinteresterification while avoiding complete deesterification of thetriglyceride. The resulting mixed ester compositions, consisting ofmono-, diand triglycerides with monoand diesters of polyoxyethyl eneglycol, are miscible with hydrocarbons and emulsifiable with water. Theready emulsifiability of these materials is the result of a substantialportion of the mixture being monoand diesters of polyoxyethylene glycolswhich are known nonionic surface active agents. US. Pat. No. 3,202,607shows the formation of polyoxyethylene adducts of castor oil containingfrom about 10% to about 80% by weight combined ethylene oxide and thecombination of the resulting adducts with propylene glycol ordipropylene glycol to provide functional fluids for use as aqueousdispersions in the working of alloys and steels.

While emulsions and dispersions of lubricant esters are acceptable inmany applications there are some common problems associated with theiruse for lubrication. Their biggest drawback is the tendency to separateupon standing. Even the best lubricant ester emulsions are not stableindefinitely and upon prolonged standing, such as during storage, theemulsions separate and thus require re-emulsification which is costlyand time-consuming. Additionally, it is often difficult to obtainuniform lubrication with lubricant emulsion systems particularly inhigh-speed operations. For these and other reasons the trend has beentoward the use of lubricants which are water soluble, as opposed tothose which are only emulsifiable or dispersible in water (see U.S. Pat.No. 3,676,345). Clear lubricant solutions are especially desirable sincethey have the added advantage that the operators can constantly visuallymonitor the lubricant and determine the amount of contaminants, such asdirt and scale, picked up during the operation.

U.S. Pat. No. 3,634,245 discloses ester lubricants which are soluble inlF water but which have distinct cloud points below l80F and a two-stepprocess for their preparation. To obtain the water soluble products ofthe invention castor oil is first transesterified with about 0.75 toabout 2.0 mol equivalents polyoxyethylene glycol having a molecularweight of at least 1000 until the reaction product is soluble, i.e.,when grams of the product are completely soluble in 100 mls of water at100F. The product is then further modified in a separate and distinctstep by reacting with a monoor dicarboxylic acid. The second reaction iscontinued until the acid number of the composition falls below about 6.This product is then diluted with water to obtain aqueous solutionscontaining about 5 to about 50% by weight of the ester product.

While the ester compositions of U.S. Pat. No 3,634,245 are usefullubricants they are not completely soluble in water at room temperatureand they have distinct cloud points below 180F. Other disadvantages arethat the process requires two distinct reaction steps and is apparentlylimited to use with castor oil if useful products are to be obtained.Additionally, in order to obtain useful ester compositions polymericalkylene oxide glycols having molecular weights of at least l000 arenecessarily employed.

It would be extremely useful and advantageous if water solubletriglycerides could be obtained employing a one-step process and if theresulting products were readily soluble in cold water to give clearaqueous solutions. It would be still more useful if a wide variety oftriglycerides and low molecular weight polyoxyethylene glycols could beused to obtain useful lubricants. The advantages of this latter featurewill become more evident as the instant invention is described morefully.

SUMMARY OF THE INVENTION We have now discovered mixed ester productsobtained by a single-step transesterification reaction of triglycerides,low molecular weight (less than 1000) polyoxyethylene glycols andshort-chain monoor di basic acids which are readily soluble in coldwater in all proportions to provide clear lubricant solutions. Aqueoussolutions of these esters have superior lubricating properties.Additionally, the present lubricants have negative heats of solution sothat while they are completely soluble in water at lower temperaturesthey come out of solution as the temperature is raised. This feature ishighly desirable in certain metalworking operations, such as hotrolling, since the ester lubricant will deposit from solution onto thesurface of the metal to provide more effective lubrication.

Over and above the desirability of having water soluble ester lubricantswith improved properties and negative heats of solution, the utility ofthis invention is enhanced by the ability to obtain these mixed esterproducts by a one-step reaction employing polyoxyethylene glycols havingmolecular weights less than i000. Ester products having theabovementioned desirable properties are not possible when high molecularweight polyoxyethylene glycols are substituted in the one-step reactionprocedure of this invention.

The ester products of the present invention are obtained by thesingle-step reaction of a triglyceride, a polyoxyethylene glycol havingan average molecular weight less than 1000, and a monoor dicarboxylicacid containing from 2 to 12 carbon atoms. Especially use-- ful in thepresent invention are triglycerides derived from predominantlyethylenically unsaturated C fatty acids, polyoxyethylene glycols havingaverage molecular weights between 400 and 800, and aliphatic acidscontaining 2 to l2 carbon atoms or cycloaliphatic and aromatic acidscontaining from 7 to 12 carbon atoms. The ester compositions willcontain from about 5 to 35% by weight triglyceride, 4 to 20 wt.carboxylic acid and about 60 to wt. polyoxyethylene glycol. The esterproducts will generally have acid values of about 10 or below. About 0.1to about 25% by weight of the ester is preferably dissolved in water toprovide the useful aqueous lubricant solutions.

DETAILED DESCRIPTION The mixed ester compositions of this invention arethe reaction products of a triglyceride, a polyoxyethylene glycol ofmolecular weight less than 1000 and a short-chain monobasic or dibasicacid. The transesterification reaction is completed in a single step toobtain the mixed esters which are soluble in cold water in allproportions to provide clear aqueous lubricant solu- 3 tions which donot separate on standing. The present lubricant esters have excellentlubricating properties.

To obtain the ester compositions of this invention any of the commonlyknown triglycerides can be em: ployed and yield water soluble mixedester products. Natural and synthetic fatty acid triglycerides includingthe drying, semi:drying and non:drying vegetable oils, animal oils andfats are useful and are within the scope of the present invention.Triglycerides of the above types include olive oil, palm oil, almondoil, ground nut oil, apricot kernel oil, linseed oil, castor oil,soybean oil, oiticica oil, tung oil, crambe oil, coconut oil, peanutoil, rapeseed oil, neatsfoot oil, cottonseed oil, tallow, lard, whaleoil and the like. The oils may be used as such or may be hydrogenated ormodified prior to use. They may be used individually or a mixture of twoor more triglycerides employed. For example, if a highly conjugatedtriglyceride such as tung oil or oiticica oil is used it may beadvantageous to include a second oil of an unconjugated nature.Especially useful triglycerides for the preparation of the instant estercompositions are those derived from predominantly ethylenicallyunsaturated C fatty acids such as oleic acid, linoleic acid, linolenicacid and mixtures thereof. Oleic:linoleic acid oils and linolenic acidoils, and more particularly linseed oil and soybean oil, are especiallyuseful triglyc: erides for use in the present invention.

The polyoxythylene glycols useful for the purpose of this invention haveaverage molecular weights less than 1000 but preferably above about 200.It is possible to employ polyoxyethylene glycols containing higher andlower molecular weight materials so long as the result: ing mixturesfall within the approximate foregoing ranges. A broad molecular weightdistribution of the polyoxyethylene glycols is generally not detrimentalto the lubricant properties, however, appreciable amounts of glycolshaving molecular weights greater than I000 should not be present ifoptimum results are to be ob: tained. Best results are obtained withpolyoxyethylene glycols having average molecular weights between about400 and 800.

To achieve the improved water soluble mixed ester compositions of thisinvention one or more carboxylic acids are included when thetriglyceride and low mo: lecular weight polyoxyethylene glycol arereacted. Use: ful acids can generally be defined as low molecular weightshort:chain mono: and dicarboxylic acids and, more specifically, containfrom 2 to 12 carbon atoms. Acids suitable for use in the process includealiphatic, cycloaliphatic and aromatic acids which contain one or twocarboxyl groups. Triand tetracarboxylic acids may also be employed ifdesired as may other polyfunc: tional compounds such as trimelliticanhydride. Useful cycloaliphatic and aromatic acids contain from about 7to 12 carbon atoms and include such acids as benzoic acid, phenylaceticacid, toluic acid, phthalic acids, p-tert butyl benzoic acid,cyclohexanecarboxylic acid, cyclohexanedicarboxylic acid and the like.Aliphatic acids can either be branched or straight:chain and can containfrom about 2 to about 12 carbon atoms. Useful aliphatic acids includeoxalic acid, malonic acid, suc: cinic acid, glutaric acid, adipic acid,azelaic acid, su: beric acid, dodecanedioic acid, acetic acid, butyricacid, valeric acid, caproic acid, caprylic acid, capric acid, lauricacid and the like. Especially useful acids for the purpose of thisinvention are aliphatic, preferably saturated and straight:chain, mono:and dicarboxylic acids containing from about 6 to carbon atoms.

Numerous water soluble mixed ester products can be obtained depending onthe ratio of reactants employed. For best results however, both from thestandpoint of water solubility and lubricant properties, the triglycer:ide will constitute about 5 to 35% by weight of the total reactantcharge with the carboxylic acid and polyoxyethylene glycol comprisingabout 1 to 20% by weight and about 60 to 85% by weight, respectively.Ex: tremely effective lubricant esters which are readily soluble in coldwater are obtained with about 10 to 30% by weight triglyceride, 5 to 15%by weight carbox: ylic acid and 65 to by weight polyoxyethylene glycol.These ester products are particularly useful if derived from linseed orsoybean oil, a C straight: chain saturated mono: or dicarboxylic acidand poly: oxyethylene glycol having a molecular weight from about 400 to800.

Numerous advantages are realized when the above: described reactants arecombined in the prescribed amounts as a unit charge and reacted in asingle step. Most importantly, ester products having good lubricantproperties and complete solubility in cold water in all proportions areobtained. Additional advantage is real: ized, however, from the factthat the so:produced es: ters have negative heats of solution.

While the above two features by themselves are use: ful and trulyunexpected, there are still other important aspects of this inventionincluding the ability to use low molecular weight polyoxyethyleneglycols, the ability to achieve water solubility with reducedpolyoxyethyl: ene glycol contents and the ability to achieve watersolubility regardless of the particular triglyceride used, which arealso useful and highly desirable features. Previously, only highmolecular weight polyoxyethyl: ene glycols could be used if watersolubility was to be achieved but it is now possible with this inventionto use low molecular weight polyoxyethylene glycols and achieve the sameresult. Somewhat related to the abil: ity to employ low molecular weightpolyoxyethylene glycols is the fact that with this invention it is alsopossi: ble to obtain water solubility using reduced levels ofpolyoxyethylene glycol. Through the use of low molec: ular weightshort:chain carboxylic acids it is possible to reduce thepolyoxyethylene glycol content by as much as 20% and still obtain watersoluble products. By so doing, the triglyceride content in the productis also increased, in some cases by as much as l0% and thus theresulting ester composition has much improved lubrication properties.Still another surprising and use: ful aspect of this invention is thefact that contrary to previously known processes which yielded watersolu: ble esters with only a few of the more compatible tri: glycerides,such as castor oil, it is now possible to ren: der a wide variety ofcommonly available triglycerides completely soluble in cold water.

While the present invention is primarily directed to water soluble mixedester products it is also possible, by utilizing reactant ratios outsidethe previously specified range, to obtain ester compositions which arenot com: pletely water-soluble but which are, nevertheless, ex: tremelyuseful for their lubricant properties. These esters are typicallyreadily emulsifiable with water with: out the use of externalemulsifying aids and the result: ing emulsions find general applicationin the treatment of fibers to reduce static charge buildup and improvethe lubricity of the fiber and they are also highly effi: cientlubricants for metal working. These emulsions havethe added advantage ofimproved stability, i.e.

resistance to phase separation over lubricant emulsions formed withexternal emulsifiers. The improved emulsion properties apparentlyresultfrom the presence of the monoor dicarboxylic acid since similarester compositions prepared in the same manner from a triglyceride andpolyoxyethylene glycol but without the shortchain carboxylic acid do notpossess these same characteristics.

The reaction of the triglyceride, polyoxyethylene glycol and monoordicarboxylic acid to obtain the useful mixed ester products is conductedin a single step in accordance with known transesterificationprocedures. The reaction mixture is typically maintained at an elevatedtemperature until an acid value less than about 10, more preferably lessthan about 6, is attained. The temperature of reaction may range fromabout 100C to about 300C but more usually will fall between about 175Cand 275C. Water formed during the reaction is removed to facilitateesterification. While the use of reduced pressure is not necessary incarrying out the reaction it is often advantageous, especially in thelatter stages of the reaction if low acid values are desired, in orderto drive the reaction to completion. Catalysts are not essential to thesuccessful completion of the transesterification, however, they areusually desirable in order to speed the rate of reaction. The amount andtype of catalyst can be widely varied. Known catalysts such astetrabutyl titanate, zinc acetate, sodium carbonate, sodium acidsulfate, p-toluene sulfonic acid, methane sulfonic acid, sulfuric acid,phosphoric acid and the like may be employed. The amount of catalystwill generally range between about 0.01 to 1.0% by weight of the totalreactant charge. Most often the catalyst charge will be from about 0.05to 0.5% by weight based on the total reactants.

The reaction may be conducted in an inert diluent which is unaffectedunder the reaction conditions employed. Hydrocarbon diluents, such asfor example xylene, are useful in this process. Preferred diluentsshould be capable of forming azeotropes with water to facilitate removalof water formed during the reaction. lf diluents are not employed, whichis the most commonly practiced method of conducting the reaction, themixed ester reaction product can be directly utilized, i.e., as obtainedfrom the reactor, without any additional treatment.

The mixed ester products of this invention consist primarily ofmonoglycerides, diglycerides, unreacted triglycerides, monoesters ofpolyoxyethylene glycol, diesters of polyoxyethylene glycol and the like.Polymeric materials may also be present in small amounts particularly ifthe low molecular weight short-chain carboxylic acid is difunctionalacid. The various constituents and the amount of each of theseconstituents present in the resulting product is governed by thereactants and reaction conditions. While the makeup may varyconsiderably depending on the reaction temperature and pressure, amountand type of catalyst, ratio of reactants and the like, thiscompositional variation is not detrimental to the lubricant propertiesas long as the reaction is conducted in accordance with the foregoingdescription and within the specified ranges of reactant ratios.

The mixed esters of the present invention vary in physical form from lowviscosity liquids to semi-solid masses. While most of the mixed estercompositions are fluid oils, highly viscous and even semi-solid productsresult if triglycerides, such as tallow, derived predominantly fromsaturated fatty acids are used. The clear liquid ester products whichflow readily at room temperature are readily soluble in cold water inall proportions and give clear aqueous lubricant solutions which do notseparate upon standing. With the more viscous oils or the semi-solidproducts it may be necessary to first heat or melt the ester productprior to addition of the water in order to obtain clear aqueoussolutions. These products are, however, readily soluble upon melting anddo not separate from solution even upon cooling. The mixed esterproducts of this invention generally have flash and fire points greaterthan 500F with 2l0F viscosities from 10 to 20 centistokes and 100Fviscosities from 60 to 120 centistokes, more preferably the 210F and100F viscosities of these products are between 12 and 16 centistokes andand centistokes, respectively.

The instant ester compositions are excellent lubricants for both ferrousand nonferrous metals and are useful for a wide variety of otherlubricating applications. They may be used as such or, as they are morecommonly employed, in aqueous solutions. Aqueous solutions areparticularly useful in forging, rolling, diecasting and metalworkingoperations, particularly where the working of hot metals is involved,since these solutions are capable of providing a thin uniform lubricantfilm on the surface of hot metals and since they also provide a highdegree of cooling. These lubricants may also be used in machiningoperations such as drilling, grinding, polishing, etc. to increase thetool life and improve the finish on the machined article. The fact thatthe aqueous lubricant solutions are clear and do not separate is alsoadvantageous. The present esters and solutions thereof may be applied tothe metal and/or metalworking elements or the metal by spraying,immersing or by similar means. To improve the efficiency of theoperation and reduce the cost, the lubricants may be collected,refiltered, if necessary, and reused.

For certain applications it is advantageous that these esters havenegative heats of solution since the lubricant esters separate fromsolution at higher temperatures and are thus deposited on the surface ofthe hot metals or where friction occurs. As a result of this platingout" maximum lubricating efficiency is provided at the points where itis needed most. This feature is also useful in certain rollingoperations where heated rolls are employed since in this way acontinuous lubricant film will be present on the surface of the roll andfriction can be minimized thereby permitting more rapid rolling whileretaining good surface quality. Numerous other advantages for lubricantshaving negative heats of solution are evident to those skilled in theart.

The esters of this invention may be formulated with other additives,stabilizers, corrosion inhibitors, and the like, and they may be blendedwith one or more other petroleum or synthetic lubricants if desired.When employed in aqueous systems the concentration of the estercomposition will normally range from about 0.1 to about 25% by weighteven though these esters mix with cold water in all proportions. Aqueoussolutions of the present mixed ester products typically have cloudpoints above F.

In addition to being useful as lubricants for metals, the esters of thisinvention also find utility in other areas. Aqueous lubricant solutionsof these esters are useful as finishing agents for polymeric fibers suchas polyolefins, polyesters, polyamides and polyacrylonitriles. Suchfinishing agents are required during the processing of the fibers intoyarns and fabrics to increase the surface lubricity of the fibers,thereby reducing the fiber-fiber friction and friction between thefibers and guides, draw pins, etc. of the process equipment. Theselubricants can be applied to the fibers by spraying, immersing or thelike. By lubricating the fibers it is possible to decrease filamentbreakage, reduce static charge buildup in the fibers and facilitate thevarious process steps. The present ester compositions are especiallysuited for use in polyester and polyamide fiber-forming operations. Theesters may also be used for hydraulic fluids, paint formulations,cosmetic formulations, oil well drilling muds and most other uses wheresynthetic ester lubricants are commonly employed.

The following examples illustrate the invention more fully, however,they are not intended as a limitation on the scope thereof. All partsand percentages in the invention are on a weight basis unless otherwiseindicated.

EXAMPLE I To a glass reactor equipped with a stirrer, thermometer,H-trap connected to a water cooled condenser and nitrogen inlet werecharged 840 grams (2.86 equivalents) soybean oil, 2380 grams (l 1.9equivalents) polyethylene glycol (PEG) having an average molecularweight of 400 and 280 grams (2.98 equivalents) azelaic acid (EMEROXH44). The weight ratio of oil:PEG 400: acid was 24:68:53. This mixturewas heated with agitation while pulling a vacuum to dry the system.Tetrabutyltitanate catalyst (0.03 weight percent based on the totalreactant charge) was then charged to the reactor and the reactionmixture heated to about 250C under a nitrogen atmosphere for about I lhours while periodically taking samples to determine the acid value(AV). After ll hours reaction the product (AV 0.19) was completelysoluble in cold water to give sparkling clear solutions. Heating wasterminated at this point. The mixed ester product had a hydroxyl valueof l4l.2 and viscosities at IF and 2l0F (ASTM D 445-65) of 78.8centistokes and 12.9 centistokes, respectively.

To demonstrate the versatility of the resulting ester and the ability ofthe product to function as a lubricant, an aqueous solution of the esterwas applied as a finish to a polyester yarn. Such finishes are commonlyused to improve lubrication at the fiber-metal interface therebyreducing the static charge accumulation on the fiber during processing.The mixed ester was applied at 0.5% o.w.f. on I50 denier polyester whichwas solvent stripped to remove any previous finish. Finishes wereapplied from aqueous solutions using an Atlab Finish Applicator. Beforetesting, the treated yarns were conditioned for 24 hours at 70F and 65%relative humidity. Frictional properties of the yarn were then measuredwith a Rothschild F-Meter holding the tension constant at [00 gramsusing a yarn speed of 100 meters per minute and a yarn/metal contactangle of 180. Static properties were determined by insulating one of thepulleys and connecting it to a voltmeter and measuring the staticbuildup" on the pulley in 8 seconds. The ester composition describedabove was compared to sorbitan monolaurate, a commercially availableproduct commonly employed for textile finishing, and shown to have alower coefficient of friction and a significantly lower voltage buildup(300 volts for the mixed ester as compared to 550 for the sorbitanester) indicating improved fiber lubricity when the mixed ester productis used as a finishing agent.

EXAMPLE ll Employing a procedure similar to that described in Example Ithe following materials were charged to a reactor:

About one-half of the tetrabutyltitanate catalyst was added at thebeginning of the heating and the remainder charged after a portion ofthe water had been removed. Heating (250C) was terminated when the acidvalue of the reaction product reached 5.3. The resulting mixed esterproduct containing about 68% bound polyoxyethylene glycol, had aviscosity of 70.6 centistokes at I00F, and was immediately soluble incold tap water with essentially no agitation.

The effectiveness of the mixed ester product of this Example as ametal-working lubricant was determined using a Falex machine. Thismachine provides a convenient and reliable method for determining thefilm strength or load-carrying properties of lubricants under extremepressures. The Falex wear test (ASTM D 2670-67) is conducted with a 60gram sample of the ester product or, if aqueous solutions of the mixedester lubricants are being evaluated, a 600 gram sample of the aqueoussolution is used. The cup containing the lubricant is positioned so thatthe steel pin and blocks are completely immersed in the sample. Themachine is started and an initial load of 300 pounds applied for 5minutes. The load is then increased to 1000 pounds and maintained for 30minutes. The difference between the readings taken at the beginning andthe end of the 30 minute periods indicates the amount of wear. The mixedester product of Example ll showed only 47 units wear. This is a markedimprovement over mineral oil of comparable viscosity which fails beforethe 1000 pound load level is reached and dioctyl sebacate which fails atthe 300 pound load level after only 30 seconds operation. A 5% aqueoussolution of the mixed ester evaluated on the Falex machine alsoregistered only 7l units wear. These results demonstrate the superiorlubricating properties of the mixed ester products of the presentinvention.

EXAMPLE lll A reaction was conducted employing identical amounts andtypes of reactants as described in Example l. Zinc acetate (0.l percentby weight based on the soybean oil) was used to catalyze the reaction.After about 5% hours of heating at 250C the acid value dropped to 0.9.The resulting lubricant ester product had a hydroxyl value of 85.6,flash and tire point (ASTM D 9266) of 550F and 590F, respectively, and a2l0F viscosity of 12.6 centistokes. The product was readily soluble incold water producing a clear solution effective as a lubricant for bothmetal and fiber uses. When the above Example was repeated usingpolyoxyethylene glycol having an average molecular weight of about 800 asimilar product was obtained.

EXAMPLES IV vn To demonstrate the versatility of this invention and theability to obtain water soluble ester lubricants with triglyceridesother than soybean oil and coconut oil, a series of runs were conductedin which PEG 400 and azelaic acid were reacted with linseed oil, palmoil. tallow and castor oil. In each of these runs the triglycerideconstituted 24% of the charge with polyoxyethylene glycol (68%) andazelaic acid (8%) making up the remainder. The reactions were allconducted similarly, following the procedure of Example I. Physicalproperties and Falex test results for the resulting ester products areset forth below. Cloud points for the esters were obtained bydetermining the temperature at which printed matter was no longerlegible through 100 mls of a aqueous solution of the ester in a 250 mlglass beaker. At room temperature and below all of these productsprovide sparkling clear solutions, however, as these solutions areheated they become cloudy.

The ability to obtain clear solutions with palm oil and tallow is trulysurprising in view of the fact that these saturated triglycerides aregenerally very difficult to even emulsify.

EXAMPLES VIII XII A series of water soluble soybean oils were preparedin accordance with the already described procedures. The polyoxyethyleneglycol used had an average molecular weight of about 400 but themodifying acids were varied to include aliphatic and aromatic monoanddicarboxylic acids. The weight ratio of soybean oilzPEG 400: acid was24:68:!3. The following table lists the various acids used and theproperties of the resulting esters.

EXAMPLE N0. ACID COMPONENT ACID CLOUD VALUE POINT (F) VIII pelargonic L4102 IX p4ert-butylbenzoic 0.5 91

X dodecanedioc I .5 l I B XI isophthalic 0.5 90

XII terephthalic 2.0 88

All these esters provided sparkling clear solutions in concentrations ofSto 25% using room temperature tap water. These esters had goodlubricating ability both as the neat oils and in aqueous solution.

EXAMPLE XIII A preparation was made using soybean oil, azelaic acid andpolyoxyethylene glycol having an average molecular weight of 2000. Theprocedure, weight ratios of reactants and catalyst were the same as inExample II. The reaction was continued until an acid value less than 10was achieved. The resulting ester product did not form a clear solutionwith room temperature water but was readily emulsifiable to provide amoderately stable emulsion.

EXAMPLE XIV Soybean oil was modified following the procedure of ExampleI except that the reactant charge was varied. In this preparation theweight ratio of soybean oil:PEG 400: azelaic acid was 2827811. The esterproduct was readily soluble in water at room temperature and had goodlubricating properties.

EXAMPLES XV XVII Palm oil, castor oil and coconut oil were charged asfollows with PEG 400 and azelaic acid:

EXAMPLE WEIGHT PERCENT OF TOTAL CHARGE Palm Castor Coco PEG Azelaic OilOil Oil 400 Acid XV 30 60 I0 XVI 30 60 IU XVII 26 65 9 EXAMPLE XVIII Theversatility of the present process and the ability to obtain usefulester products using low molecular weight short-chain carboxylic acids,even though the reactant ratios are outside the defined ranges, isevident from the following preparation where soybean oil, PEG 400 andazelaic acid were reacted at a weight ratio of 90:624.Tetrabutyltitanate was used to catalyze the reaction which was carriedout at 220C. The ester obtained (AV 5.4) did not form a clear solutionwith water but was readily emulsifiable in water without the use ofexternal emulsifying aids. The ester had viscosities at I00F and 210F of44cS and 9.2cS, respec' tively, with a 550F flash point and 625F firepoint. A 5% aqueous emulsion of the ester showed essentially no wear atthe end of the standard testing period in the Falex machine while theneat oil gave only 49 units wear.

We claim;

I. A water soluble mixed ester product obtained by the single-steptransesterification of:

a. a triglyceride selected from the group consisting of animal oils,animal fats, drying vegetable oil, semi drying vegetable oils andnon-drying vegetable oils;

b. a polyoxyethylene glycol having an average molecular weight fromabout 400 to 800; and

c. a carboxylic acid containing one or two carboxyl groups and from 2 tol2 carbon atoms; said reactants (a), (b) and (c) respectively comprising5 to 35%, 60 to and l to 20%, by weight, of the total charge.

2. The water soluble mixed ester product of claim I wherein (a) isderived predominantly from C fatty acids containing ethylenicunsaturation and (c) is an aliphatic acid.

3. The water soluble mixed ester product of claim 2 having an acid valueless than about 10 with flash and fire points greater than 500F, a 2l0Fviscosity from about 10 to 20 centistokes and a IF viscosity from about60 to 120 centistokes.

4. The water soluble mixed ester product of claim 2 wherein (a) is anoleiclinoleic acid oil or linoleic acid

1. A WATER SOLUBLE MIXED ESTER PRODUCT OBTAINED BY THE SINGLE-STEPTRANSESTERIFICATION OF: A. A TRIGLYCERIDE SELECTED FROM THE GROUPCONSISITNG OF ANIMAL OILS, ANIMAL FATS, DRYING VEGETABLE OIL,SEMI-DRYING VEGETABLE OILS AND NON-DRYING VEGETABLE OILS; B. APOLYOXYETHYLENE GLYCOL HAVING AN AVERAGE MOLECULAR WEIGHT FROM ABOUT 400TO 800; AND C. A CARBOXYLIC ACID CONTAINING ONE OR TWO CARBOXYL GROUPSAND FROM 2 TO 12 CARBON ATOMS, SAID REACTANTS (A), (B) AND (C)RESPECTIVELY COMPRISING 5 TO 35%, 60 TO 85% AND 1 TO 20%, BY WEIGHT, OFTHE TOTAL CHARGE.
 2. The water soluble mixed ester product of claim 1wherein (a) is derived predominantly from C18 fatty acids containingethylenic unsaturation and (c) is an aliphatic acid.
 3. The watersoluble mixed ester product of claim 2 having an acid value less thanabout 10 with flash and fire points greater than 500*F, a 210*Fviscosity from about 10 to 20 centistokes and a 100*F viscosity fromabout 60 to 120 centistokes.
 4. The water soluble mixed ester product ofclaim 2 wherein (a) is an oleic- linoleic acid oil or linoleic acid oiland (c) is a saturated, straight-chain aliphatic mono- or dicarboxylicacid containing from 6 to 10 carbon atoms.
 5. The water soluble mixedester product of claim 4 where (a) is linseed oil or soybean oil.
 6. Thewater soluble mixed ester product of claim 4 wherein the reactant chargeis comprised 10 to 30% (a), 65 to 75% (b) and 5 to 15% (c).